Colombia-Related Matters (Loss Contingencies) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013 victim lawsuit
ATS Lawsuits [Member]
Loss Contingencies [Line Items]
Number of civil tort lawsuits filed against the company	9
Minimum number of alleged victims at the balance sheet date	6,000
Number of lawsuits seeking unspecified compensatory and punitive damages as well as attorneys' fees and costs	8
Number of lawsuits seeking treble damages and disgorgement of profits without explanation	1
Specific demand in compensatory damage	$ 10
Specific demand in punitive damage	$ 10
ATA Lawsuits [Member]
Loss Contingencies [Line Items]
Number of civil tort lawsuits filed against the company	4
Number of lawsuits for which the motion to dismiss was granted in part and denied in part	1
Number of lawsuits dismissed after the parties reached a confidential settlement agreement	1